febrile seizure

Last edited 01/2022 and last reviewed 01/2022

Febrile convulsions or febrile seizures are benign, generalised convulsions seen in children aged between six months and five years associated with fever in the absence of intra-cranial infection, metabolic disturbance, or history of afebrile seizures.

  • these age limits are arbitrary and should only be used as a guide (1,2)
  • there is no universal agreement regarding the level of fever required to diagnose febrile seizure,
    • consensus guidelines recommends that the axillary temperature should be >37.8°C (3)
    • the American Academy of Pediatrics (AAP) defines temperature to be  >= 100.4°F or 38°C by any method (4)
  • diagnostically they must occur in a developmentally normal child, last for less than 20 minutes, be generalised with no complex features, and leave no residual abnormality

The International League Against Epilepsy (ILAE) defines a febrile seizure as:

“a seizure occurring in childhood after one month of age associated with a febrile illness not caused by an infection of the central nervous system, without previous neonatal seizures or a previous unprovoked seizure, and not meeting the criteria for other acute symptomatic seizures.” (1)

Febrile seizures occurring in a child older than one month during an episode of fever affect 2-4% of children in Great Britain and the United States and recur in 30%. (5)

  • a systematic review found reduced recurrence rates for intermittent diazepam and continuous phenobarbital, with adverse effects in up to 30% of children (5)

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